1. Field of the Invention
This invention relates to a catalyst for the production of ethylene oxide and a method for the production of ethylene oxide, and in particular to a catalyst excellent in selectivity for ethylene oxide that enables ethylene oxide to be produced in a high selectivity, and a method for the production of ethylene oxide using this catalyst.
2. Description of Related Art
Industrial production of ethylene oxide by the catalytic vapor phase oxidation of ethylene with a molecular oxygen-containing gas in the presence of a silver catalyst is broadly conducted. Many technologies are proposed concerning the carrier, the supporting method, the reaction promoter and the like in relation to the silver catalyst to be used for the catalytic vapor phase oxidation.
For example, a carrier containing α-alumina as the main component and having a predetermined median pore diameter and a predetermined pore volume, and a catalyst using this carrier are disclosed in JP-A-2000-44331 as a technology for controlling properties of a carrier composing a catalyst. For another example, a technology for controlling the surface area and water absorption of a carrier so as to be at predetermined values and controlling the pore volume and pore diameter of a carrier so as to have a predetermined relation is disclosed in WO 03/072244 and WO 03/072246.
Although the catalytic activity, selectivity and catalyst life of a silver catalyst are already at a high level, these catalytic performance are still required to be improved. Taking selectivity as an example, the amount of the raw material, ethylene, to be used is remarkably saved leading to a marked economic effect by improving the selectivity by only 1%, because of a large production scale of ethylene oxide. Under these circumstances, development of a silver catalyst having higher performance has been an incessant research theme in the related technical field.